152 BIRDS OF TUNISIA 



and are composed of grasses and root-fibres, lined with horsehair and 

 a few feathers. The eggs, four to six in number, are a dull white, 

 clouded with pale brown, and measure about 20 x 15 mm. 



MOTACILLA BOREALIS, Sundevall. 

 SLATE-HEADED WAGTAIL. 



Motacilla fiava borealis, Sundev. (Efr. K. Vct.-Akad. Forh. Stockh. 



ISIO, p. 53. 

 Motacilla borealis, Sharpe, Cat. Birds Brit. Miis. s, p. 522, pi. vii, 



figs. 1-3 ; Kocnig, J. f. 0. 1893, p. 25. 

 Budytes flavus borealis, Erlanger, J. f. 0. 1899, p. 322. 

 Motacilla viridis, Whitaker, Ibis, 1895, p. 96. 



Description. — Adult male, spring, from Hadj-el-Aioun, Central Tunisia. 

 Differs from M. flava in having the crown and sides of the head darlier, 

 no white superciliary stripe, and no white on the chin or throat. 

 Soft parts and measurements as in M. flava. 

 Adult female duller in coloration than the male. 

 The young are hardly distinguishable from those of the preceding forms. 



Observations. — Examples are occasionally found with a slight white 

 supercilium, and a little white on the chin. 



My Tunisian collection contains only two or three specimens of 

 this Wagtail, which were obtained in spring. The form does not 

 appear to be nearly so abundant in the Regency as either of the two 

 preceding ones, and I have no knowledge of its nesting anywhere in 

 that country. It is, in fact, supposed to breed much further north 

 than any of the other Yellow Wagtails. In Tunisia it may sometimes 

 be met with in the company of M. flava, from which species it 

 probably does not differ much, if at all, in its general habits. 



